In all fairness to your parents, they're probably still getting their heads round the fact that you've flown the nest. Their protective instincts are probably multiplied many times over by the fact that they don't really have any control over your life any more. Whilst what they've said is misguided, I agree with the people who've said not to condemn them, or tell them they're racist or xenophobic or whatever...
Have you introduced them to your eastern european friends? Might help them to understand more about them, and make them less nervous.